Phenolphthalein is one of the most commonly used chemicals in the field and laboratory to indicate the presence of blood. Our pre-packaged kit contains all the reagents to conduct a presumptive blood test. This simple four-step test is easy to use and is housed in a small plastic cup. An immediate pink color on the end of the swab indicates a presumptive positive for blood. 60 tests per kit. These are refills for parts A, B and C. Parts A, B & C Refills 500ml each (≈2,000 Tests Per Kit)